Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $240.54   9.160%   $262.5735   $262.57   $262.55   $262.60  
  Purchase #2 $246.67   9.390%   $269.8323   $269.83   $269.85   $269.80  
  Purchase #3 $170.46   11.298%   $189.7186   $189.72   $189.70   $189.70  
  Purchase #4 $13.33   5.258%   $14.0309   $14.03   $14.05   $14.00  
  Purchase #5 $156.91   5.402%   $165.3863   $165.39   $165.40   $165.40  
  Purchase #6 $52.51   8.798%   $57.1298   $57.13   $57.15   $57.10  
  Purchase #7 $226.69   4.265%   $236.3583   $236.36   $236.35   $236.40  
  7 purchase totals = $1,107.11       $1,195.0297   $1,195.03   $1,195.05   $1,195.00